A description of the visual characteristics of some constricted discharges in the rare gases using dc, rf, and microwave excitation is given. These discharges require power inputs of from 20 to greater than 100 W/cc. The results of a series of spectroscopic and electrical measurements made on these discharges indicate the range of plasma parameters encountered. Gas temperatures were measured using the intensity distribution of the spectra of several diatomic molecules. The gas temperature falls in the range from 2000° to 3000°K, but atomic excitation levels are not in equilibrium at this temperature. The charge density is around 1014/cc from continuum intensity, line broadening, and electrical measurements. The electron energy distribution is Maxwellian with an average electron energy which falls between 1 and 2 eV. Thus, these plasmas lie between ``thermal'' and ``cold'' plasmas in their properties. The recombination process probably has contributions from both dissociative recombination and dielectronic recombination with an over‐all recombination coefficient of about 2×10−11cm3/sec.